This disclosure relates to a testing device for analyzing the amount of particles shed from medical devices during implantation into or manipulation through the bodily tissues of a human being. The Food and Drug Administration has long required that device manufacturers characterize the amount of particle shedding from implantable medical devices during the lifetime of the implanted device. A number of inventions have been developed to rapidly accelerate testing conditions to artificially simulate implant conditions over a long period of time. It is known, for example, that implantable medical devices such as stents, heart valves, and in vivo blood filters tend to shed particles from material coatings or from the device material itself over long periods of time. A heart stent, for example, will experience several million heartbeat cycles throughout its implant lifetime. Several inventions allow rapid acceleration of the testing of such devices in the implanted condition. For example, a medical device durability tester will condense a lifetime of heartbeat cycles into a few years by accelerating the replicated heart cycles at a pace much faster than encountered in the normal human condition. Thus, a lifetime of heartbeats can be condensed into a much shorter period of time. Some durability testing devices incorporate particle shed counters while others rely on particulate filters to capture shed particles for microscopic counting.
While several medical device durability test units are commercially available, until now there has not been a device specifically configured to ascertain particle shed that may occur as an implant or other medical device is maneuvered into position within the human body. Medical implants delivered by catheter, such as stents, blood filters, and catheter-delivered heart valves are usually implanted through human vasculature. For example, a heart stent may be implanted through a femoral artery in a patient's inner thigh. Other devices may be manipulated through human tissues that resist movement or require tortuous manipulation of the device. Thus, the implant or other device travels a relatively long and tortuous pathway through the human vasculature or other body tissue to the implant or usage location. There is concern that the process of implanting such devices through the vasculature or other body tissue may result in particle shedding from the device due to rubbing and vasculature pressure. Further, for devices deployed via catheter, it is necessary to determine counts of particles shed from the catheter. It is important to analyze the count of particles shed during implantation as part of a medical protocol in anticipation of FDA review and approval of such devices.
Accordingly, applicant's invention substantially replicates the conditions experienced during medical device implantation through human vasculature or manipulation through body tissues. Conditions such as vasculature pressure, temperature, pH, length of implant travel, and the travel pathway must be substantially replicated for accurate testing with this invention.